The Chilean Paradox: Why Are Cases Rising Despite High Levels of Vaccination?

[This document is a one of a series of discussion notes addressing fundamental questions about the COVID-19 crisis and response strategies. These documents are based on the best scientific information available and may be updated as new information comes to light.]

This document has been written by Clara Marín, Leire Pajín Iraola, Gonzalo Fanjul, Oriana Ramírez, Jeff V Lazarus, Adelaida Sarukhan (ISGlobal), Báltica Cabieses (Universidad del Desarrollo), Catterina Ferreccio (Pontifical Catholic University of Chile), Paola Salas, Manuel Nájera and María Jesús Hald (Chilean Epidemiology Society).

UPDATE ON 28 JULY, 2021. Since the publication of this document, Chile has continued implementing non-pharmaceutical preventive measures and restrictions and vaccinating its population so that now over 60% of its inhabitants have been fully vaccinated. The case incidence started to decrease by mid-June and currently stands at around 1300 new daily cases; this represents a considerable reduction with respect to the dates analysed in the report. The improvement in Chile’s situation shows the importance of combining non-pharmaceutical interventions with a strong vaccination campaign in response to the pandemic.

With more than half of its population fully vaccinated by mid-2021, Chile is at the top of the list of countries with the highest COVID-19 immunisation rates. However, transmission, far from decreasing, has increased to the maximum recorded in the country: the incidence rate as of 13 June was 362.57 per million population, the tenth highest in the world, and the occupancy rate or intensive care units (ICUs) was 95%. Chile is experiencing the worst moment of the pandemic. How is this contradiction possible?

This document analizes Chile’s vaccination strategy, one of the most successful in the world, and what went wrong. One major problem has been the early loosening of restrictions and the high level of mobility within the country, because of the austral summer holidays. But algo the high inequality and “too little, too late” social support measures. In addition, vaccination in Chile has mostly been carried out with the Sinovac vaccine, which is very effective (80%-90%) at preventing hospitalisation, severe disease and death but only 67% effective at preventing infection. And there have been some communication failures.

Chile serves as a cautionary tale for other countries that are now vaccinating much of their population: it is not enough to immunise the public—at least not for the time being. 

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